Pathophysiology Of Epilepsy
Neuronal messages are transmitted by electrical impulses called the Action Potential. This is actually a net positive inward ion flux that leads to depolarization or voltage change in the neuronal membrane. The ions involved include sodium, potassium, calcium and chloride. Normally brain tissues prevent hyper excitability by several inhibitory mechanisms involving negative ions like chloride ions.
There are two types of transmission of impulses - excitatory and inhibitory. Excitatory transmission involves Glutamate that is the principal excitatory neurotransmitter in the brain. GABA or Gamma amino butyric acid is the principal inhibitory neurotransmitter in the brain.
There are two groups of glutamate receptors -
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These abnormally discharging epileptic neurons recruit adjacent neurons or neurons with which they are connected into the process. A clinical seizure occurs when the electrical discharges of a large number of cells become abnormally linked together, creating a storm of electrical activity in the brain. Seizures may then spread to involve adjacent areas of the brain or through established anatomic pathways to other distant areas.
On a fundamental level, seizures can be viewed as resulting from an imbalance between excitatory and inhibitory processes in the brain. Proposed mechanisms for the generation and spread of seizure activity within the brain include abnormalities in the membrane properties of neurons, changes in the ionic micro environment surrounding the neuron, decreased inhibitory neurotransmission which is primarily by gamma-amino butyric acid (GABA), or enhanced excitatory neurotransmission which is primarily mediated by the acidic amino acid,
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The synchronized bursts from a sufficient number of neurons result in a so-called spike discharge on the EEG. At the level of single neurons, epileptiform activity consists of sustained neuronal depolarization resulting in a burst of action potentials, a plateau-like depolarization associated with completion of the action potential burst, and then a rapid repolarization followed by hyperpolarization. This sequence is called the paroxysmal depolarizing shift. The bursting activity resulting from the relatively prolonged depolarization of the neuronal membrane is due to influx of extracellular Ca++, which leads to the opening of voltage-dependent Na+ channels, influx of Na+, and generation of repetitive action potentials. The subsequent hyperpolarizing after potential is mediated by GABA receptors and Cl− influx, or by K+ efflux, depending on the cell type.
Summary Of Mechanism of seizure formation
• Excitation of a group of nerves. This is caused by inward currents of Na, Ca and involvement of excitatory neurotransmitters like Glutamate and Aspartate.
• Too little inhibition.
• Epileptogenesis and hyperexcitability and hypersynchronization of neurons that facilitates spread. There has to be abnormal synchronization – a property of a population of neurons to discharge together independently. Alone, a hyperexcitable neuron
By definition, “Epilepsy occurs when nerve cells in the brain send electrical messages at a rate
Seizure are uncontrolled or sudden abnormal electrical activity in the brain which causes abnormal motor and sensory activity and where the patient becomes unconsciousness. It is caused by the depolarization of the neurons. Any changes that takes place in our body that may be internal or external it can easily stimulate the irritable neurons. Seizure last for a second or a minute, in which the neurons stops unexpectedly. The pattern of electrical activity or brain waves during a seizure can be seen in EEG, by knowing what type of seizure. There are different
People uneducated about Epilepsy may have confused thoughts on what it really is. People have these "notions," which are partly or entirely not true. So, throughout this research paper, these notions will be proven untrue, mostly by factual information given by
The constant firing of neurons in the brain during normal everyday actions is called electrical brain activity. Seizures are changes in the brain's electrical activity, which can "cause dramatic, noticeable symptoms or even no symptoms at all (healthline.com)." During a seizure, nerve cells leave their regular positions where they delivered orders from the brain to other parts of the body. The neurons fire in
Pathophysiology of epilepsy- Epileptic seizures arise from an excessively synchronous and sustained discharge of group of neurons [9].Abnormal cellular discharges may be associated with various causative factors such as trauma, oxygen deprivation, tumors, infections. Although different types of epileptic syndromes differ pathophysiologically, ictogenesis related mechanisms are often common. It is generally accepted that ictogenesis results from hyperexcitability of neuronal membrane. Both neurotransmitters and ion channels play a crucial role in neuronal excitability[9]. Excitability is a crucial feature of ictogenesis that may originate from individual neurons, neuronal environment and population of neurons. Excitability arising from single
Glial cells deliver neuroactive molecules and adjust synaptic transmission through modifications in ion channels, gap junctions, receptors, and transporters (4). Shape and function of glial cells change considerably in various kinds of epilepsy. Dysregulation of water and ion channel expression, variations in secretion of neuroactive molecules, and increased activation of inflammatory pathways as well as reactive gliosis Morphologic changes include (4). It has been suggested that epilepsy has an astrocytic origin (8). Prolonged neuronal depolarization and epileptiform discharges are resulted from direct stimulation of astrocytes (9) .
Epilepsy is a disorder caused by reoccurring seizures. This occurs because of excessive firing of the neurons and fast spread of these impulses over the brain. There are two pathophysiology phenomenon of a seizure: Hyper-excitability of a neuron and hyper synchronization (Prayson, & Jordan, 2015). Hyper synchronization is the hyper-excitable neuron that leads to increased excitability of a large surrounding area of neurons. Basically, a large electrical impulse is generated in one part of the brain from this excessive firing in the neurons. Seizure is defined as an “involuntary alteration of behavior with or without loss of consciousness accompanied by an abnormal electrical discharge in the brain” (Offringa, & Moyer, 2011). The key part of
Epilepsy is one of the most popular neurological diseases, affecting up to 1% of the adult and 2% of the paediatric populations. An epileptic seizure is the result of some functional disorders occurring in the brain and is formed as a result of an abnormal, excessive electrical discharge in nerve cells. The cause of a seizure is a sudden imbalance between excitatory and inhibitory processes in the neural network.
Epilepsy is classified as a chronic neurological disorder characterized by repetitive seizures. Recurring seizures are caused by disruptions in the brain's nerve cell activity. These disruptions can result in seizures, odd behavior, strange sensations, and in some cases blackouts or loss of consciousness. Epilepsy covers a large spectrum of brain disorders that range from benign and minor to severe and life-threatening or disabling.
Over 65 million people in the world today suffer from some form of epilepsy. This condition, consisting of a set of neurological illnesses that create seizures, has never been fully cured or even understood through the course of modern medical history. The root cause of epilepsy largely remains a mystery even today but a handful of scientific breakthroughs in recent decades have allowed for the millions of individuals who suffer from this condition to find some relief. The abnormal nerve cell activity occurring in the cortex that leads to the seizures that represent epilepsy has not been harnessed and controlled but it now can be manipulated and mitigated through a combination of different treatments and practices. Through a concise review
Epilepsy Research Paper People most often associate violent twitching, falling to the floor and drooling with epilepsy. However the described event is only one kind of an epileptic seizure, which is called a tonic-clonic seizure. There are many other kinds of seizures, and each has different sets of signs and symptoms. During generalized seizures the whole brain is affected and the initial symptom is loss of consciousness. This category includes such seizures as absence seizure, myoclonic seizure, and atonic attack.
Epilepsy is a neurological infirmity that involves repeated, involuntary seizure activity [1]. The seizures are produced by the sudden burst of hyperactivity in the brain, causing strange sensations, body stiffening, loss of memory or behaviour, jerking of arms and legs etc. More than 2% of the population are affected by epilepsy. The seizure symptoms may differ from one person to another and can be triggered by various factors which include brain injury or brain tumour, alcohol or drug effects, genetic disorders and infections. Quick diagnosis and early treatment is essential to avoid any dangerous and life threatening situations [2].
4. Antagonism of Glutamate: is the primary excitatory transmitter in the CNS. This work through two receptors’ NMDA receptors (N-menthel-D-aspartate receptors) and AMPA receptors (Apha_amino-3-hydroxy-5-methyl_4- isoxazole propionic acidrereceptors), - This action suppress neuronal excitation
Epilepsy is a neurological condition that affects the nervous system and may also be referred to as seizure disorder. A person may be diagnosed with epilepsy or seizure disorder after having two or more seizures with no related medical condition (epilepsy.com, 2014). According to Dr. Dimitri P. Agamanolis, seizures arise from a neurotransmitter dysfunction causing interference between the electrical activity and the brain. Approximately 25% of seizures are a result of genetic inherited abnormalities. Another 25% of documented seizures arise from structural lesions including; brain tumors, brain trauma, infections and perinatal brain lesions. All of these presentations stem from environmental influences and not congenital in nature.
Epilepsy may develop because of an abnormality in brain wiring or an imbalance of nerve signaling chemicals called neurotransmitters. (Epilepsy (epileptic), n.d.) The symptoms of epilepsy are seizures and they fall into these categories. Simple Partial Seizures